A simple, but painfully hard to figure out Oasis problem

[newmarokie]

OK. Had the coach out last weekend for a ballgame. We tried to fire up the oasis for some heat. It sputtered a couple of times and then quit even sputtering. We got to plug in eventually and the AC side kept us from freezing Saturday night. Got home and tinkered with it. Opened it up and cleaned the nozzle, stem, and filter. No joy. Got it moved to the shop on Monday and really dug into it. Checked the solenoid valve. It was functioning. Checked the ignitor, it was good. Checked the flame sensor, it was working. I disassembled the regulator, it checked out. In studying the regulator I realized the back side is open to the atmosphere. I could take a #6 machine screw and gently push in and the burner would get fuel a fire up. Pull the screw out and the flame went out. OK< I'm stumped. I call ITR and visit with a tech. I didn't get his name, but he enlightened me on a thing or two. The regulator works off of vacuum. The burner draws the fuel to itself from the venturri created mixing the fuel and air. He said the system would work with the fuel line dipped into a cup or fuel. Hmm. I took the fule line loose and put it in a cup of fuel and tried to start it and the fuel line was blowing bubbles. Not good. I finally found the right size O-ring to replace the old one on the stem. Still didn't work but just a few bubbles. OK, maybe I need to tighten the stem into the tip. Worse bubbles. So I took the stem and nozzle out of the tip and put a 5/32" x 9/32" x 1/16" O-ring on the nozzle where it sits in the stem. There was not any sign of one there when I took it apart. Run it up in the tip good and snug. Reassembled everything and it fired right up. About forty cents of parts and six hours of labor and it is working. Does anyone know if that last O-ring I put in is supposed to be there? It could be that my nozzle and stem are worn and just not sealing good. I have searched for a good schematic to no avail

 

[MemoriesByTheMile]

I am not following where the o-ring was.
But do know that when a tiny o-ring on the stem failed for us in the past that the burner would not work.
We carry spare o-rings now, super cheap.

 

[newmarokie]

Memories, there is an O-ring at the bottom of the stem where it goes in the burner body. It separates the air from the fuel until it gets to the nozzle. I put a very small O-ring between the tip and the stem. I was losing air there and putting back pressure on the incoming fuel. The same result as the O-ring at the base being bad. I did finally find a service paper on this on the ITR website. It doesn't show or talk about an O-ring at that end. My thoughts are if it fails the burner quits working. If it doesn't fail, Yah!!